[taylanub]

I also started thinking things along the lines of that when I first looked into how Guix does things, but after annoying the developers a little (many thanks to Ludovic's patience) I've come to understand that things like that beat the whole purpose of having pure packages not only in binary content but also in run-time behavior.

Basically, reproducible builds are a red herring here. A package's identity is not only the hash of its byte-by-byte contents, it also includes ("closes over") the identities of all packages it "references" (depends on), meaning it will always have the exact same run-time behavior everywhere because even all its dependencies count as part of its identity.